1. Field
Embodiments relate to a complementary metal-oxide-semiconductor (CMOS) image sensor, and more particularly, to a back-side illumination CMOS image sensor having an anti-absorption material formed on an interface between an anti-reflection layer (ARL) and a photodiode. Embodiments relate to a CMOS image sensor including a photodiode that includes regions having different refractive indices.
2. Description of the Related Art
CMOS image sensors convert an optical image to an electrical image. Recently, as information and communications technology has developed and digital electronic devices have become ubiquitous, CMOS image sensors having improved performance have been used in various devices such as digital cameras, camcorders, mobile phones, personal communication systems (PCSs), game machines, security cameras, and medical cameras. As the increase in integration of semiconductor products has accelerated and thus the size of a unit cell has greatly decreased, a line width in a pattern and a distance between patterns have decreased significantly. Although the size of a unit cell is reduced, electrical characteristics and low power consumption of a device should be maintained.
As the degree of integration of pixels has increased in order to achieve increased resolution for a CMOS image sensor, the volume of a photoelectric conversion element, e.g., a photodiode, per unit pixel has decreased, thereby reducing sensitivity.